THE EXPERIMENTAL INVESTIGATION ON THE COURSE OF ESTABLISHING CORONARY COLLATERAL CIRCULATION OF THE HEART IN RABBIT / 解剖学报

ABSTRACT

The course of estahlishing coronary collateral circulation has been studied after ligating the anterior descending branch of the left coronary artery (L. A. D.) of the heart in 20 rabbits. Another 5 rabbits were studied as control group. The experimental results were as follows (1) The rabbit electrocardiograms EGG were made before and after the ligation of the L. A. D. The EGG of control group was made only before killing. In these experiments, the pathological changes of No. 28 were observed immediately after ligating the L. A.D. It was found that the T wave was inverted in standard lead I, and that the volts of the QRS complex in lead Vc fell apparently. This phenomenon may be interpreted as myocardial ischemia in the anterior wall of the heart. After ligating the L. A. D. the S-T segment of No. 27 in AVL lead elevated and exceeded I mm, and the depressive Q wave in Vc lead was greater than the one-fourth of the R wave before killing. All of the phenomenen observed in the rabbit entirely confirmed the myocardial infarction and myocardial ischemia. In No. 25, the T wave was inverted in standard lead I, and the QRS complex in lead Vc was not only shallow in depth but also very little. The conditions accounted probably for myocardial ishcmia. During 4 to 21 days after ligating the L. A. D.,the pathological changes in the EGG occurred frequently.The rabbit ECG gradually became normal from 21 st day on. (2) The coronary arteries of the rabbit hearts were injected with X-ray contrast medium and were examined. The X-ray film thus obtained were compared with the specimen after they were cleared. At the same time, sections of the heart walls (the infarcted area and its surrounding areas) of fifteen rabbits were studied carefully under microscope. Our primary impression was that only a few newly formed vessels in the central part of the infarct till the fourth day after ligating the L. A. D. The vessels surrounding of the infarct show a slight winding and distension. During 10 to 28 days, the number of the newly formed vessels in the infarct increased gradually day by day. The vessels surroundings the infarct were also highly crooked and distended, especially in the anterior wall of the right ventricle. This is possibly the most active period in the establishment of coronary collateral circulation. During 28 to 49 days, the morphology of the vessels in the infarct area became similar to that of the corresponding area of the control group. (3) The significance of the coronary collateral circulation on the heart wall was discussed.